Fuse plug



Nov. 27i,' 1923.

8 E 5 9L RP 5. o P 7 TA 4 N m6 T 5 E. G. AP'PLETON FUSE'VPLUG I Filed Ma 7.1921

ATT t' Patented Nov. a, 1923;.

UNITED STATES PATENT OFFICE.

ERNEST G. APPLE-TON, OF CHICAGO, ILLINOIS, ASSIGNOR TO CHICAGO FUSE MFG. (10., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

FUSE PLUG.

Application filed May 17, 1921. Serial No. 470,250.

To all wkomit 12mg] concern: I

Be it known that I, ERNEST G. APPLETON, a citizen of the United States, residing at Chicago, in'the county of Cook and State of Illinois, have invented certain new and useful Improvements in Fuse Plugs, of which the following is a. specification.

The invention relates to fuse plugs of the renewable type, and more particularly to a fuse plug of sectional construction in which a refillable fuse casing of the cartridge type is clamped between the separable sections of the plu'g.

The common type of fuse plugs is constructed with a fusible element,permanently fixed to the plug terminals and upon the fusing of which the plug is discarded or re turned to the makers for reconstruction. It is highly desirable that such plugs may be constructed for continuous use and provision made for the ready renewal of the fusible element carried by the plug.

. It is one of the objects of this invention to provide an electric fuse plug which is adapted for continuous use, and which may be refilled by the user at slight expense.

Anotherobject is to provide a fuse plug in which the fusible link is contained within a refillable cartridge of improved structure adapted for the quick and easy replacement of the link when fused.

A further object is to provide a fuse plug in which a looselyassembled cartridge fuse is securely clamped between readily separable sections of the plu In the ordinary use 0 a cartridge fuse, it is necessary to secure the metallic ends of the cartridge to the insulating casing within which is located the fusible link. This construction is required because of the explosive force of the {gases generated with the fusion of the link which otherwise would blow the caps from the ends of the casing with damaging effect.

In my construction, I have provided for the use of loose end caps on the cartridge casing which are merely slipped over the ends of the casing and which are rigidly secured when assembled in the fuse plug by a novel construction of the parts of the latter whereby the end caps are securely clamped in position, one of the caps functioning at the same time as oneof the contact terminals of the plug. This simple construction materially reduces the expense of manufacture of the plug and greatly facilitates the renewal of the fusible element.

Other objects and advantages will be apparent in the following detailed description of a preferred embodiment of my invention, which I have illustrated in the accompanying drawings. It is to be understood, however, that in the interpretation of the appended claims they are not to be limited to the precise construction and arrangement set forth except as may benecessitated by the state of the prior art. I

In the drawings, longitudinal section takenv through the assembled plug. Fig. 2 illustrates the. separable parts of the plug disassembled as when renewing the fusible link.

As illustrated herein, my invention comprises a Inetallicshell 10 of tubular form and constructed of sheet metal, one endintegrally closed, as indicated at 11. The tubular portion of the shell is shaped with spiral corrugations developing internal and external screw threads. The open end of the shell is adapted to-be received in the customary socket common in electrical construction and forms one of the contact terminals of the plug.

The closed end of the shell is externally covered with an insulatingcap 12 which I prefer to secure to the shell by means'of molding thecap in a plastic state aboutthe end of the shell. The plastic material, filling the corrugations in the outer surface of the shell, thereby precludes lon itudinal dis placement when hardened. ative rotation,

F ifgure 1 represents ao prevent relone or more indentations may be struck in the end wall of the shelland extending into the structure of the cap as indicated at 13.

Carried within the open end of the shell and extending internally for the greater portion of its depth is a sleeve 14: constructed of any suitable insulating material, and having overa portion of its outer periphery screw threads 15 adapted to engage the internal threads formed in the tubular wall of the shell. A portion. of the sleeve cictends outwardly from the shell as at 16, and may be knurled to provide a convenient gri p for turning the sleeve i l; in and out of engagement with the shell. The knurled porlion alsoservcs as an indicator to a person not familiar with the plug, of the fact that the section or sleeve 14; isintended to be unscrewed and removed. The extended portion also provides necessary longitudinal spacing between the end of the shell and the center terminal of the plug to prevent short circuiting of the terminals in the receiving socket.

The sleeve 14; is further constructed with an axial bore 17 cxtendii'ig therethrough, the. bore being restricted at the outer end of the sleeve to produce an annular shoulder 18 on the inner wall of the sleeve. Located within the bore is a cartridge fuse comprising a casing 19 constructed of fiber or other suitable insulating material, within which is positioned a fusible link 20. The link is of sutlicient length so that its ends may be bent over the ends of the casing and extend along the outside wall of the casing as at 21.

Overlying each end of the casing is a cupshaped metallic cap 22 slidably enclosing the casing end and establishing electrical contact with the respective ends of the fusible link. The inner edge of each cap is turned radially outward to form an annular flange 23 which loosely engages the inner side wall of the bore 17. The casing 19 is of such length that when the caps are in place the total length of the assembled cartridge is slightly more than that of the sleeve it within which it is positioned.

The shoulder 18 is spaced from the outer end of the sleeve 14; by such distance that the cap 22 on the outer end of the cartridge, which extends through the restricted portion of the bore, is permitted to protrude a slight distance beyond the end of the sleeve, with the flange 23 formed on the inner end-of the cap in abutment with the shoulder. The protruding portion of the outer cap thus forms the central contact terminal of the assembled plug when the latter is positioned in the ordinary socket.

With the outer cap so positioned, the inner cap will likewise extend a slight distance beyond the inner end of the sleeve. lVhcn so assembled within the sleeve, and the latter screwed into the shell 10, the inner cap is clamped against the end wall 11 of the shell making electrical contact therewith. Both caps are'thus rigidly held in position upon the casing 19 in secure contact with the fusible element 20, and without possibility of displacement upon the disruption of the fuse.

The casing 19 being of smaller outside.

diameter than the bore in which it is positioned is maintained centrally of the bore iterates by means of the flanges 23 formed on the caps. To provide an exit for lhc gases generatedv with the fusion of the fusible link,

a vent 2- may be formed in the wall of the casing 19., thrii'ugh which the gases may escape into the space between the casing and the inner wall. of the bore, and thus through the bore around the flange :33) of the inner cap, to the chamber about the inner end of the sleeve l l within the shell. fcape for the gases from this chamber may be provided for by a passage 25 running through the end wall of the shell and its outer insulating cover 12.

It will here be noted that the gases, in traveling through the plug a re forced through a tortuous passage and are cooled to a safe degree before they are permitted to escape from the oulcr vent.

It will also be apparent that in the assembled plug the end caps are securely clamped upon the fuse casing, and are held thereby against the possiliiility of being blown off from the casing by the explosive force of the gases generated with the fusion of the fuse link. lly my construction it is possible to avoid the use of screw threads or other fastening means ordinarily necessary to secure the end caps upon the casing, and provide for free engagement of the caps on the using ends. This arrangement effects a material saving in the cost of construction of the cartridge member, and also greatly facilitates the disassembling and reassembling of the parts in renewing the fusible link.

It will now be apparent that I have provided a renewable fuse plug in which no part of the plug is destroyed or rendered useless with the blowing of the fuse except the fusible link, and that the plug is so constructed that it may quickly and readily be disassembled for the insertion of a renewal fusible link.

My construction is adapted for unlimited use and is of simple and inexpensive construction accomplishing a high degree of cliicicncy in operation and economy in use.

I claim as my invention:

1. A fuse plug comprising a metallic shell, an insulating sleeve rcmovably secured therein, a tubular l'usc casing within said sleeve, metallic end caps on said casing. and means operable by the assembly of said sleeve with said shell for rigidly positioning said casing and end caps with one cap in contact with said shell and the other cap extending outwardly from said plug.

2. A fuse plug comprising a threaded metallic shell having a metallic end closure, a removable insulator having threaded cngagement with said shell, and a renewable cartridge fuse having loose end caps, said cartridge fuse being clamped in rigid assembly between said metallic closure and said insulator, one of said caps extending through said insulator to form a contact terminal.

3. A fuse plug comprising a metallic shell having a transverse metallic end Web, an insulating sleeve threaded internally of said shell, a tubular casing carrying a fusible element and-positioned within said sleeve, and metallic end caps on said casing having contact with said element, one of said caps extending a limited distance through the outer end of said sleeve and being engaged thereby to clamp the other of said caps in contact with said end web.

tallic contact shell having a metallic closure at one end, an insulating sleeve extending within the open end of said shell, an insulating tube positioned in said sleeve, metallic end caps on said tube, and a fusible link extending between said caps within said tube, said sleeve being adapted to clamp said tube within said shell with-one of said caps in abutment with said metallic closure, and

with the other of said caps protruding from the outer end of said sleeve to form a contact terminal.

I tubular fuse casing having metallic end caps positioned in said bore, one of said. caps abutting the restricted portion of said bore and. protruding from said sleeve, the other ofsaid caps protruding from the inner end.

of said sleeve in abutment with the end Wall ofsaid shell. I

6. A fuse plug comprising a metallic shell having an end wall, an insulating sleeve removably secured in said shell and extending outwardly from one end, said sleeve having a central bore restricted at its outer end to form an annular shoulder, a tubular insulating casing positioned within said bore and spaced from the walls thereof, metallic endcaps on said casing having radial flanges adapted, to centrally position said casing in said bore, one of said caps extending through the restricted portion of said bore with its flange in abutment with said shoulder, the other of said caps .being clamped against the end wall of said shell, and a renewable fusible element extending between said end caps. v

7. A fuse plug comprising an outer contact shell, a tubular insulator Within said shell, a fuse casing positioned within said insulator and carrying a fusible link, terminal caps on the ends of said casing, and flanges on'said caps loosely engaging the inner Wall of said insulator tospace said casplug comprising a threaded me respective sections, one section having an annular terminal exteriorly threaded to screw into a socket and internally threaded for detachable engagement with the other section, said last mentioned section having an opening through which one end of said carrier projects to constitute the central termiv nal of the plug. 4. A fuse plug comprising a tubular me- 9. A fuse plug compr sing a tubular 0011- tact shell having an end wall, a tubular fuse casin having flanged metallic end caps loose y fitted thereon, an insulating sleeve having screw-threaded engagement within said shell and adapted to receive said casing with said end caps partially protruding from 'the ends of said sleeve, said sleeve having an inner shoulder arranged to engage one of said flanged end caps to prevent passage in one direction and thereby force the other of said end caps in contact with the end wall of said shetlil when said sleeve and shell are assemble v i 10. In a fuse plug having separable telescoping sections, the combination of an'insulating casing, a fusible link extending through and overlying the ends of said casing, a metallic cap slidable over each end of said casing and in contact with said link, and a radial flange formed on each of said caps, said caps being clamped between the separable sections of said plug to prevent displacement from said casing. I

11. A fuse plug comprising, in combination, a cartridge which includes-an insulating carrier, metallic end caps thereon and a fusible element extending along said carrierand in contact with said caps, and a body portion comprising two readily separable sections, one section having an annular metallic terminal, a rigid end wall and a. metallic part located at the inner side of said end wall and electrically connected to said terminal, the other section being removably threaded into said terminal and having an opening-through its end opposite said rigid end Wall through, which opening one-of the caps of said cartridge projects, and means to limit the extent to which said cap may project from said opening, the opposite cap 1 0 being in contact with the part located at the inner side of said end Wall, and the said end wall constituting an abutment for the last mentioned cap wherebywhen the two sections are screwed together, the cartridge will v be securely clamped between the sections.

12. A fuse plug comprising, in combination, a fuse carrier, a body comprising two readily separable sections having means to clamp the ends of said carrier between the respective sections, one section comprising an annular terminal and the other" sectionhaving an opening through which one end of said carrier projects to constitute the central terminal of the: plug.

13. A fuse plug comprising, in combination, a body ha'ving 'an annular terminal and an inner chamber, a fuse carrier in said chamber, a central terminal at one end of said carrier, a cap at the other end of said carrier in lnl testimony whereof, I have hereunto 15 set my hand.

ERNEST G. APPLETON. 

